Stabilizer for elevatable platforms



P. G. PRITZ July 29, .1941.

STABILIZER FOR ELEVATABLE PLATFORMS Filed July 5, 1940 2 Sheets-Sheet l INVENTOR PE ERG.PR|T2 Y ATT RNEY STABILIZER FOR ELEVATABLE PLATFORMS Filed July 5, 194

2 Sheets-Sheet 2 P. G. PRITZ I I Patented July 29, 1941 UNITED STATES PATENT QFFICE 1 Claim.

The object of the invention is to provide improvements in stabilizers, but more especially in that type which is designed to stiffen or rigidify plunger elevated platforms, such as are employed in elevatable loading platforms, elevatable stages for use in so-called night clubs and the like.

Heretofore, each such structure has comprised the usual horizontally extending platform per se, a pressure-actuated plunger or equivalent elevating means, and suitable means for operatively and rigidly securing said platform and plunger together, but without adequate means to prevent the platform from tilting when unevenly loaded. The plunger has frequently been of dual construction, that is, a pair of centrally positioned plungers separated by a few feet and operated in unison, where greater power is required than can be expected from a single plunger within feasible size limits. Aside from possible guide rails, there has to date been no support whatever for the freely extending end or laterally opposite side portions of the platform, other than that afforded by the centrally positioned plunger (or plungers) and the nominal rigidity of the platform itself. As a result, platforms of considerable length and/or width, such as those having marginal portions eight feet, ten feet, twelve feet and even more distantly removed from the central support, tilt noticeably as performers (or other active or dead weight load) shift their positions, such as when dancing, tumbling or going through other forms of movement.

An object of the invention, therefore, is to provide additional supports for one or more of the remotely positioned portions of the platform, and preferably at the same time to so construct such additional supports, that they will at the same time serve as positive guides to prevent lateral as well as vertical angular movement of the platform.

A further object is to so construct the improved device, that it will be relatively inexpensive to manufacture and operate, while fulfilling every desired feature of a perfectly rigid object of the class mentioned.

With the objects thus briefly stated, the invention comprises further details of construction and operation, which are hereinafter brought out in the following description, when read in conjunction with the accompanying drawings, in which Fig. 1 is a top plan view of a device comprising one embodiment of the invention, with a portion of the platform removed; Fig. 2 is an enlarged fragmentary vertical section of a portion of the same; Fig. 3 is an enlarged horizontal section through one of the lateral guide-supports; Fig. 4 is a perspective view of a portion of the device partly broken away to show interior portions of the same; and Fig. 5 is an enlarged fragmentary portion of the device, showing one of the lateral supports per se.

Referring to the drawings, an elevatable platform such as used for loading and unloading merchandise at various levels, for theatrical and night club performances, et cetera, is shown as comprising basically a substantial flooring I, provided with an upper surface 2 of hard wood, composition or other suitable material. Said flooring is laid upon a frame of end and side channel irons 3 and 3a, which are rigidly secured together at their corners by any suitable means 6, while an additional channel 5 is secured by similar means 8 to the side irons 3 in spaced relation with the end irons (id, as shown in Figs. 1 and 2. Approximately but not necessarily in the center of the platform the laterally opposite and usually parallel side channels 3 are rigidly connected together by an additional pair of channels 1, secured in place by suitable fastening means 8, and also secured together by means of preferably horizontally extending sections of I- beams 9, the webs is of which lie in the same horizontal plane and rest directly upon and are secured to the upwardly extending heads ll of parallel plungers 12, which are adapted to reciprocate vertically within casings iii. The lower end of each of these casings preferably rests upon a metallic plate I l, embedded in a concrete foundation l5. while the upper portions of said casings are surrounded and unitarily connect'ed by a surface layer of concrete I6, each of said casings being provided with a head I! to which is detachably secured a removable cap l8. Within an intermediate portion of. each casing an annular ring [9 is provided, such ring being secured in fixed position by bolts or the like 20 to form with the cap is a guide for said plunger.

Preferably at each of the opposite ends of the platform, the transversely extending pairs of channels 3a and 5 are connected together by horizontally extending sections of broad channels 2|, to the under surface of each of which is secured the head 22 of a plunger 23, the lower portion of which plunger slides through an annular ring 24, secured by bolts 25 or the like within a vertically extending casing 26. The lower end of each of these last mentioned casings rests upon a metallic plate 21 embedded within a concrete foundation 23, while the upper portion of each such casing extends through the surface layer of concrete I6. In addition, these laterally positioned casings may be maintained in absolutely fixed relation with respect to the one or more centrally positioned plunger casings by means of spacer bars, tubes, or the like 29, which may be embedded within said surface layer and instead of terminating short but in the neighborhood of adjacent casings may, if desired, abut directly thereagainst.

When two or more central plungers are used, their casings are preferably tied together by a cross-braced unit and parallel side bars 3|. Secured to these bars, as by welding, and also preferably welded to the upper portions I! of said plunger casings are suitably shaped brackets 32 carrying oppositely directed pulleys 33, which are aligned in each instance with a pulley 34 carried by bands 35 surrounding the upper portions of the respective lateral casings 26, said last-mentioned pulleys being actually rotatable within openings 34 in said last-mentioned casings. The free end or pulley-supporting portions of the said brackets 32, pairs of which are preferably in substantial alignment, may be additionally unitarily secured together by means of straps 32a, thereby relieving a large portion of the tension which would otherwise be placed upon the rivets, bolts, welding, or other means, by which said brackets are secured to said casing heads. A preferably flexible cable, ribbon or band 35, provided with a tension-regulating turn-buckle 36 is secured at one end, preferably to one or more of the bolts holding the horizontal I beam webs ID to the plunger heads ll, thence downwardly through apertures 35 in said webs around the pulleys 33,

over the pulleys 34 and thence into and downwardly through the lateral casings 26, thence loosely through U-shaped apertures 31 in the rings 24 beneath the lower ends of the guide elements 23 and finally secured at their opposite ends to transversely extending pins 38 within the lower-most portions of the said respective elements.

In the operation of this device, and assuming that the platform 2 is in its lowermost position level with the surface of the surrounding floor, fluid pressure within the lower portion of the one or more casings l3 forces the corresponding plunger or plungers l2 upwardly, thereby directly elevating the central portion of said platform until an increase in fluid pressure ceases and the said plunger or plungers have reached either an intermediate or the extreme limit of their normal path of movement. Simultaneously each of the secondary elevating elements 23 are raised so as to elevate the laterally remote portions of said platform in direct accordance with the central lifting force, as well as with one another, such lifting of said secondary elements being accomplished by means of the flexible cables 35, hereinbefore described. Furthermore, as said platform rises, the space that would be otherwise opened between its periphery and the adjacent portions of the surrounding floor or platform is operatively sealed to all intents and purposes by means of a depending flange or skirt 39, which in addition to being attached to and comprising a depending extension of the elevatable platform, is also supported by securing the same two blocks, stringers, or other type of filling means 40 of wood or the like, secured tightly within the peripherally extending channels 3 and 3a, as indicated in Figs. 1 and 2. The surrounding fixed flooring or platform 4| is of any desired material'and construction, and so will not be described herein as being of any particular tyDG. As no invention is involved in the method by which fluid pressure is led into the elevating plunger or plungers l2, no pipes or other form of conduit are herein illustrated, it being understood that they may be of any size and position as they lead into the lower portion of the respective one or more casings l3. Obviously, however, where two or more primary lifting means are employed, the pressure upon them must be equal at all times and simultaneously applied or released, as the case may be.

Further than the foregoing, it is to be understood that the broad principles involved are in no way dependent upon the details of the platform per se, as herein illustrated and described, while instead of the secondary lifting elements 23 being of plunger-like construction, they may instead comprise dovmwardly depending I-beams or the like, either without or operatively associated with suitable guides to prevent them from shifting angularly in a lateral direction under the downward tension due to the weight of the platform and the upward tension applied through the lifting cable 35. Similarly other details may be altered from those more or less specifically illustrated and described herein without departing from the scope of the invention.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent of the United States is:

The combination of a platform, with a peripheral channel iron supporting frame comprising side and end members, a centrally positioned pair of spaced parallel channel irons extending transversely of and secured to the opposite side members of said frame, channel irons within, spaced from and parallel with each of the end members of said frame, a plate spanning the spaces between said central pair of channel irons, plates spanning the spaces between said lastnamed channel irons and their adjacent end members, a vertical substantially centrally positioned supporting plunger secured to said first plate, a pair of vertical supporting plungers secured to said last-mentioned plates and positioned upon the opposite sides of said first plunger, a cable connecting the upper portion of said first plunger with the lower portions of said last-mentioned plungers, and pulleys for guiding said cable so that a rise of said central plunger causes an equal rise of said end plungers.

PETER G. PRITZ. 

